A Review of the Physiology of the Gastrointestinal Tract in Relation to Radiation Doses from Radioactive Materials

For some methods of calculation, the fraction of the 24 hr during which a section of the GI-tract is full of food residues is required (“occupancy factor”). Suggested values for this factor are as follows: stomach 6/24, small intestine 14/24, upper large intestine 18/24 and lower large intestine 22/24. It is suggested that the effective radius of the GI-tract as a whole be taken as 10 cm: that the radius of the stomach be taken as 10 cm, and of the small intestine also as 10 cm; that the upper and lower large intestine each be taken as 5 cm in radius. The following topics are also discussed: geometrical factors in irradiation of the GI-tract by its contents: sites of absorption of different substances in the GI-tract: distances of food residues in the GI-tract from mitosing cells: dose to the ovary from the contents of the GI-tract.